I'm not a aikido-ist, but I've had some friends who were very high level. They explained to me the origin of aikido was as a technique that policemen could use with plausible deniability. When people watch someone fight against an aikido-ist they see: "The guy charged at him and something happened and then the guy ran right into that lamp post and knocked himself out".

Whether that is really true, or I misinterpreted what I was told, I'm not sure, but I always find it an amusing thought.